可控深度电法对水平柱体和垂直界面的计算和实验

球状地球体可控深度电法的效应系数可近似地全面表达可控深度电法和各种效应。通过点源二度体的电算模拟实验，证明了该方法在水平柱状体和地下存在电阻率垂直界面的条件下，也是有效的。     

A mathematical hysteretic model for elastomeric isolation bearings

An analytical model for high damping elastomeric isolation bearings is presented in this paper. The model is used to describe mathematically the damping force and restoring force of the rubber material and bearing. Ten parameters to be identified from cyclic loading tests are included in the model. The sensitivity of the ten parameters in affecting the model is examined. These ten parameters are functions of a number of influence factors on the elastomer such as the rubber compound, Mullins effect, scragging effect, frequency, temperature and axial load. In this study, however, only the Mullins effect, scragging effect, frequency and temperature are investigated. Both material tests and shaking table tests were performed to validate the proposed model. Based on the comparison between the experimental and the analytical results, it is found that the proposed analytical model is capable of predicting the shear force–displacement hysteresis very accurately for both rubber material and bearing under cyclic loading reversals. The seismic response time histories of the bearing can also be captured, using the proposed analytical model, with a practically acceptable precision. Copyright © 2002 John Wiley & Sons, Ltd.     

Tests on low‐ductility RC frames under high‐ and low‐frequency excitations

The response of low‐ductility reinforced concrete (RC) frames, designed typically for a non‐seismic region, subjected to two frequencies of base excitations is studied. Five half‐scaled, two‐bay, two‐storey, RC frames, each approximately 5 m wide by 3.3 m high, were subjected to both horizontal and/or vertical base excitations with a frequency of 40 Hz as well as a lower frequency of about 4 Hz (close to the fundamental frequency) using a shake table. The imposed acceleration amplitude ranged from 0.2 to 1.2g. The test results showed that the response characteristics of the structures differed under high‐ and low‐frequency excitations. The frames were able to sustain high‐frequency excitations without damage but were inadequate for low‐frequency excitations, even though the frames exhibited some ductility. Linear‐elastic time‐history analysis can predict reasonably well the structural response under high‐frequency excitations. As the frames were not designed for seismic loads, the reinforcement detailing may not have been adequate, based on the crack pattern observed. The effect of vertical excitation can cause significant additional forces in the columns and moment reversals in the beams. The ‘strong‐column, weak‐beam’ approach for lateral load RC frame design is supported by experimental observations. Copyright © 2001 John Wiley & Sons, Ltd.     

Study on effects of damping in laminated rubber bearings on seismic responses for a ⅛ scale isolated test structure

The effects of damping in various laminated rubber bearings (LRB) on the seismic response of a ?‐scale isolated test structure are investigated by shaking table tests and seismic response analyses. A series of shaking table tests of the structure were performed for a fixed base design and for a base isolation design. Two different types of LRB were used: natural rubber bearings (NRB) and lead rubber bearings (LLRB). Three different designs for the LLRB were tested; each design had a different diameter of lead plug, and thus, different damping values. Artificial time histories of peak ground acceleration 0.4g were used in both the tests and the analyses. In both shaking table tests and analyses, as expected, the acceleration responses of the seismically isolated test structure were considerably reduced. However, the shear displacement at the isolators was increased. To reduce the shear displacement in the isolators, the diameter of the lead plug in the LLRB had to be enlarged to increase isolator damping by more than 24%. This caused the isolator stiffness to increase, and resulted in amplifying the floor acceleration response spectra of the isolated test structure in the higher frequency ranges with a monotonic reduction of isolator shear displacement. Copyright © 2002 John Wiley & Sons, Ltd.     

Slump-initiated and controlled syndepositional sandstone remobilization: an example from the Namurian of County Clare, Ireland

Remobilization of sandstones can dramatically reconfigure original depositional geometries and results in very unusually shaped sandstones, which resemble little, if any, of the original geometry. A number of deformational sandstone bodies, dykes and volcanoes from the upper part of the Carboniferous Ross Formation are described, which offer the opportunity to examine a suite of field-scale reconfigured sandstones. These structures are located in close proximity to the Ross Slide, which outcrops along a 2-km section on the northern coast of the Loop Head Peninsula, County Clare, Ireland. Dome- and ridge-shaped deformational sandstone bodies, dykes and volcanoes are interpreted to be the product of remobilization of a turbiditic sandstone. Liquification and remobilization were triggered by translation, cessation and loading of the underlying turbiditic sandstone by the Ross Slide. Deformational sand body, dyke and volcano development occurred in an asynchronous fashion with deformational sand bodies formed during slump translation. Sand dykes and volcanoes developed after the cessation of slump movement. During slump translation, the minimum principal stress (σ₃) was orientated vertically and the slump behaved in a `ductile' manner. After slump arrest, the minimum principal stress was oriented horizontally, and the unit regained shear strength to behave in a `brittle' manner. The relative change in rheological states with changing applied shear stress is indicative of thixotropic-like behaviour within the slump mass. Ridge-shaped deformational sand bodies are aligned parallel to slump folds, and their morphology is inferred to be controlled by compressional slump deformation associated with heterogeneous cessation of slump movement that was initiated by frontal arrest of the translating mass.     

可调滞回模型的磁流变阻尼器及其试验

本文在现在磁流变阴尼器性能研究的基础上，提出了可调滞回模型的磁流变阻尼器及其试验方法，并进行理论、试验及算例分析。首先，根据恒定电流下磁流变阻尼器的阻尼力滞力特性，利用磁流变材料特性的电流（即磁场）可控特点，建立了变电流下的阻尼力滞回模型；其次，在中通过电路板控制外加电流与装置变形间的函数关系，实现了变电流调节的阻尼力滞回模型；最后，将磁流变阻尼器与橡胶隔震装置结合，形成智能磁流变隔夺装置，并对一个单自由度隔震结构进行了数值仿真分析。     

均匀土-箱基-结构相互作用体系的计算分析

采用通用有限元程序ANSYS，针对捱动台试验中的均匀土-箱基-结构试验进行了三维有限元分析，计算中土体的本构模型采用等效线性模型，利用面-面接触单元考虑土体与基础交界面的状态非线性。计算表明，基础底面和土体发生滑移，基础侧面和土体之间发生了滑移和脱离，上部结构柱顶加速度反应主要由基础转动引起的摆动分量组成，通过与试验结果的对照研究，二者得出的规律基本一致，验证了采用的计算模型与分析方法的合理性，为进一步计算研究和实际工程应用奠定了基础。     

桥梁隔震体系振动台试验研究(III)——测试结果分析

根据前文所述的测试结果 ,本文主要分析了隔震构造、橡胶支座水平刚度、地震输入频谱特性、地震烈度、输入方向、桥墩高度、桥墩嵌固程度等因素对隔震效果的影响 ,揭示了隔震体系耗散地震能量输入的机理 ,所得出的结论对工程实践具有指导意义。     

Hybrid vibration experiments with a bridge foundation system model

In order to improve seismic design technology of bridges, it is necessary to evaluate the vibration characteristics of a bridge–soil system that consists of soil, foundation structure, pier and superstructure. However, there have been few experimental studies on seismic behavior of bridge–soil system. In this paper, we conducted the hybrid vibration experiment on seismic behavior of bridge–soil system, and examined the applicability of hybrid vibration experiment to study seismic response of bridge–soil system. Based on the experiment results, seismic response of bridge was quantitatively studied.     

液化场地桩-土-桥梁结构动力相互作用振动台试验研究进展

本文在全面归纳与总结液化场地桩－土－桥梁结构动力相互作用振动台试验及与之相关领域的国内外研究进展基础上，直接针对我国桥梁工程中的主要震害问题，提出在我国开展液化场地桩－土－桥梁结构动力相互作用振动台试验研究的必要性，并阐述作者对液化场地桩－土－张桥梁结构动力相互作用振动台试验中若干问题的认识。